Cryogenic cooling devices.sup.1) are low-temperature cooling machines in which a thermodynamic cyclic process is running. A single-stage refrigerator comprises a working space in which a displacer reciprocates between two dead centres OT and UT. Related to the displacer is a regenerator through which a working gas also reciprocates corresponding to the motion of the displacer. During the reciprocating motion of the displacer, heat is continually withdrawn from the housing of the refrigerator in the area of one of the two dead centres. With a single-stage refrigerator of this kind it is possible to generate temperatures down to about 30 K. Often refrigerators are of a dual-stage design (refer to DE-A-38 36 884, for example). With dual-stage or three-stage refrigerators it is possible to generate temperatures down to below 10 K. In the refrigerator according to the mentioned document, a gas drive is employed to produce the reciprocating motion of the displacer. For this, a cylinder and piston arrangement is related to the warm side of the displacer whereby said arrangement must be supplied with a driving gas. FNT .sup.1) Translator's note: The term .sub." refrigerator" is also used for these cryogenic cooling devices. The term .sub." refrigerator" will be used in this sense in this translation.
Refrigerators of the kind affected here must be equipped with additional control facilities, through which the supply of the working gas into the working cylinder and also the supply for the gas drive is controlled. It is common to employ helium both as the working gas and the driving gas. In designs of this kind, it is sufficient to equip the refrigerator with two connections, one of which is supplied with high pressure helium (20 bar, for example) and where the other is supplied with low pressure helium (5 bar, for example).
During the motion of the displacer, forces occur which are greatest at the dead centres. These forces are transferred to the housing of the refrigerator and thus also to any connected devices. Generally, such devices will be highly sensitive measuring instruments (nuclear magnetic resonance tomographs, electron beam microscopes, for example), the measurement results of which are adversely influenced by the occurring vibrations. In the past, several proposals have been made to dampen these interfering vibrations. From the European Patent 19 426 it is known to arrange a damping arrangement between a refrigerator and an electron beam microscope, but this arrangement is relatively involved. From European Patent Application 160 808 it is known to arrange a flat spring within the working space of a refrigerator. Said flat spring takes up a certain amount of space within the working space so that the efficiency of the refrigerating machine is reduced. In DE-A-38 36 884 it is proposed to separate, in time, the cooling process from the measurement process. This solution requires complex control arrangements and reduces the time available to the measurements.